An airbag is one of safety devices for automobiles and its installation rate recently increases. When the collision accident of automobile happens, the impact is sensed by a sensor and inflator generates a gas with high temperature and high pressure. This gas inflates the airbag rapidly, whereby preventing and protecting especially human heads from colliding with a steering wheel, a windshield, pane and the like when the body of driver or passenger flies out to the direction of collision.
Conventionally, a coated fabric which is coated with synthetic rubber such as chloroprene, chlorosulfonated olefin, silicone and the like has been used for airbags because they have high heat resistance, high air blocking ability (low air permeability), and high fire retardancy. Currently, silicone coating is mainly used.
However, since the above-mentioned fabrics coated with synthetic rubber are heavy and their flexibility is not satisfactory and, further, their manufacturing costs are high, there are many drawbacks in using them as a fabric for airbags. Their edgecomb resistance is also poor, and therefore improvement is required. In addition, recycling characteristics are bad.
Further, in the above-mentioned fabrics coated with synthetic rubber, especially when an amount of coating is reduced, self-extinguishing property cannot be achieved and therefore improvement is required.
Although it is conventionally known to improve fabric properties by changing an amount of coating (see, for example, JP 5-16753A), there is no description on inflating properties of airbags and the like. In addition, air permeability and fire retardancy are not satisfactory. Therefore, improvement is required.
A method is proposed, which allows recycling a silicone-coated fabric by immersing the fabric into an alkali solution followed by drying and, then, by peeling off the silicone coat layer (see, for example, JP 2001-180413A). However, since a step for peeling off the silicone coating layer is necessary, manufacturing cost increases.
An invention is proposed, in which cross-linked elastomer is coated on a fabric for lightening and cost reduction (see, for example, JP 2001-524624A). However, there is no description on fire retardancy, and then improvement is required. Additionally, it is unpleasant to use cross linked resin because a cross linking process requires some amount of heat, resulting in increase of a manufacturing cost and deterioration of recycling characteristics.
Currently, uncoated fabrics for airbags without coating are mainly used, which are light and excellent in a packing property (see, for example, JP 4-281062A). However, airbags close to passengers, such as side airbags, are required to have a more rapid inflating property and, therefore, a fabric for airbags standing high pressure inflation is required.
An impregnating treatment with a diluted synthetic resin solution is proposed to form a fabric for airbags which have a high edgecomb resistance while maintaining lightness and good packing properties which are characteristics for an uncoated fabric (see, for example, JP 11-222776A). However, tear strength and low air permeability are not satisfactory.
An airbag in which an uncoated fabric and a reinforcing fabric are detachably laminated is proposed (see, for example, JU 7-22867A). However, since the reinforcing fabric is coated with heat resistant coating, it is difficult to recycle them.
Many other means are proposed for an uncoated fabric capable of being recycled (see, for example, JP 8-192705A, JP 9-11832A, JP 11-78747A). However, since an uncoated fabric has high air permeability, they are poor in human body-restraint performance when airbags inflate.